1. Field of the Invention
The present invention relates generally to torque wrenches for dental components. More particularly, the invention pertains to an improved dental torque wrench having an adjustable torque limiting assembly for use with dental implants.
2. Description of the Prior Art
In dentistry, the installation of dental implants is precision work that involves the use of tiny screws and other components that must be manipulated within a patient's mouth. Due to very limited space and visibility, this work can often become problematic. Great care must be taken by the dentist so that the implants are properly installed and so that screws and other fixtures or hardware are not dropped down the throat of a patient.
Torque wrenches are known to be a useful and important tool in this type of work. The dental implant screws must be engaged at a particular maximum torque setting. Additionally, a proper installation of the dental implant requires a consistency of torque settings for the all of the screws of a particular dental implant. The recommended torque setting will often vary between manufacturers of different implants, so the ability to be able to adjust the maximum torque setting of a wrench would be a desirable feature.
Various prior art torque wrenches devices are known in the art. For example, U.S. Pat. No. 5,295,831 issued to Patterson et al. discloses a dental implant torque wrench constructed of a single shaft of predetermined material and dimension such that application of a predetermined torque to the dental component through the shaft produces a deformity in the shaft to prevent over torquing. While this device serves to provide a satisfactory torque wrench, it suffers from the clear disadvantages of being unadjustable to varied torque settings and being difficult to manipulate in the close quarters of the mouth when each turn of the wrench requires repositioning of the screw bit on the screw or dental component.
U.S. Pat. No. 5,129,823 issued to Hughes discloses a tool for the installation of an abutment or screw in implant dentistry. The tool has a knob manually rotatable on one end of an arm and a bit, releasably secured on a sprocket, rotatable inside the patient's mouth in response to rotation of the knob. Similar to the present invention, the Hughes device can be maintained motionless during installation procedure as the knob is rotated, which is unlike conventional ratcheting mechanisms. However, the Hughes suffers from the distinct disadvantage of being unable to apply a maximum torque setting, which is a critical feature needed in implant dentistry.
U.S. Pat. No. 3,852,884 issued to Lazarus discloses an angle drive manually-operated tool for winding and tightening around a tooth with a pre-formed dental matrix band. The tool having a palm grip rotatably mounted on one end of an elongated rotatable driving member and on its other end a replaceably mounted flexible drive sleeve unit with a pre-angled guide shaft internally and pivotally suspended therein. Unlike Hughes and the present invention, the end of the tool or palm grip of Lazarus remains stationary while it is the elongated rotatable driving member that is manually turned with the fingers. This manner of operation may be satisfactory for use with a dental matrix band, but does not allow for the precision operation involving small screws and components associated with implant dentistry. Furthermore, the Lazarus device does not have a torque limiting means that is adjustable to varied torque settings.
As will be described in greater detail hereinafter, the implant torque wrench of the present invention differs from those previously proposed and employs a number of novel features that render it highly advantageous over the aforementioned prior art.